Long Distance Dispersal via Catastrophic Events

When I give my lecture in class about animal distributions, questions often are raised about how did animals get to some remote islands or even islands that are not that far off from the mainland. Sometimes the answer is that during ice ages the oceans was up to hundreds of meters lower than it is today and so there were land “bridges” between islands or even between continents. For example, the Bering land bridge between Alaska and Siberia allowed at least one route of migration for people to North America. But how did animals get to New Zealand or some Polynesian islands? How about the Hawaiian Islands. What about several species of elephants that used to live on the Island of Crete in the Mediterranean Sea? All of these islands are separated by very deep water with no chance of a land bridge in the recent past.

This dock from Japan recently showed up on a beach in Oregon. It took 15 months to make its journey across the Pacific Ocean. In the coming years thousands of additional pieces of material from that catastrophic event are expected to appear all along the Pacific coast. Image credit: AFP/Oregon Parks and Recreation

A few days ago we were reminded of the power of rare yet powerful natural events that can have long term effects far from the location of that event. The picture to the right is off a dock that washed ashore in Oregon 15 months after it was dislodged by a tsunami from its point of origin in Japan. Drifting across the entire Pacific Ocean it now find itself on a distant shores and the seaweed and some other small animals and algae that are attacked to the dock are mostly ones that are found only in the western Pacific Ocean. It is possible now that some of these organisms will make a home on the Oregon coast. Here a natural process has introduced new species to a place far from their original residence. Or course, in the past there weren’t large barges but massive tsunamis are recorded on the sides of sea-side mountains in various parts of the world. Waves 5 times as high as the Japanese tsunami would have carried thousands of tons of trees and other natural debris into the ocean. For islands withing a few hundred miles of the coast, rodents and other small animals could survive on the vegetation rafts long enough to make it to a new home. Of course a breeding pair would have to make it or at least one pregnant female in order to form a reproducing colony.

Those that study islands have noted a relation ship between the diversity of animals and plants on islands and the proximity of islands to the main land. This diversity can partially be explained by the relative chances of rare events such as these resulting in animals making it to new locations. One of the most unique but animal sparse places in the world are the islands of Hawaii. There are NO amphibians (frogs/salamanders) and NO reptiles (lizards, geckos) that are native to the Hawaiian Islands. There are frogs and lizards there today but they were most certainly all brought there by people. There are only two native (before man) mammals on Hawaii. Those are the Hawaiian Monk Seal and a Hawaiian fruit bat. Both of these are unique (endemic) species to the islands. While rare events can explain how some animals might get to some islands of the world (even a place like New Zealand) Hawaii is 2000 miles from the nearest continent. Even material from this tsunami is not predicted to begin to wash up in Hawaii for a few more months. Even the most durable mammal or reptile is going to have difficult time living on a log in the ocean for 20 months.

The Hawaiian Islands are volcanic by origin. When the first Hawaiian Island rose up out of the ocean by volcanic processes it is not difficult to imagine that abundant plant and animal life would not have characterized the first island. Where then did the plants and animals of the islands come from? There is universal (at least I’ve never heard any other explanation even from young earth creationists) that the plants and animals that are there now migrated in some way to the islands. The lack of animals other than a bat that is able to fly and a seal which can swim is not surprising. Even the presence of birds, butterflys, freshwater fish, fungi, and 10s of thousands of species of plants is really amazing considering the 2000 miles of ocean that must be crossed. There presence there isn’t just the result of their making it there but they must also have been able to find the right habitat to grow and survive and be able to reproduce. For animals, even birds this is especially difficult. One bird might be blown out to sea by a storm and get disoriented and fly 2000 miles just barely making it to Hawaii but without a mate it would be doomed to go extinct. Even two birds would still need to find the appropriate food source when it arrived and their reproduction would have to be very successful in order to establish a new population.

Of course, the plants and birds are also different species than anywhere else in the world so if they migrated from the continent to where they are today why are they not the same at continental species? But, that is a story for another day. Today, we are just reminded that rare, extraordinary, events can explain unusual phenomena such as horses or elephants on islands.

Comments

In his review of Jonathan Sarfati’s ‘The Greatest Hoax on Earth? Refuting Dawkins on Evolution’ at Amazon.com (which I’ve also read and reviewed at Amazon) scientist David Levin mentioned briefly how the formation of the Hawaiian islands is very difficult for young Earth creationists to account for in a 6,000 year scenario. In October 2010 he posted a much more detailed challenge concerning Hawaii under another review of the same book by YEC Jon Covey (he’s also repeated the challenge under some of the other reviews of ‘Hoax’ at Amazon.com). This challenge – which Dr Sarfati was unwilling to address when he was posting in discussions under some of the reviews in 2010 – did not concern natural history, rather it was to do with the northwestward movement of the islands over time, including the speed of this, and the radiometric ages of the igneous rocks on the separate islands (the southeastern islands are the most recent) .

Ashley. Absolutely right. The Hawaiian Islands are a huge challenge for YEC. Considering the significance of the islands in plate tectonics, confirmation of radiometric dating and adaptive evolutionary mechanisms the silence from YEC on the Hawaiian Islands is quite deafening. There has been nothing but a token ad-hoc explanation for some radiometric dates in their literature. I have spent considerable time investigating the Hawaiian Islands with respect to what they have to say about the age of the earth and will be presenting more of that research in the future. For now I would just add to my post that given the great difficulty of organisms getting to the islands the tremendous abundance of life on the islands today is very difficult to explain as accidental/rare dispersals to the islands over only 4000 years. Considering man has been there for 2000 years then that compresses when all this stuff got there any more. I expect that some lay Christians may suggest that God could have just transported thousands of species there miraculously but I have found that YECs are highly reluctant to employ such an explanation and prefer a “natural” explanation. But if they wish to use a “natural” explanation then it rightly can be criticized.

Here is a flavour: “Is it possible that kangaroos made it to Europe and died out? It is possible, and I would leave open such an option. What we do know is that kangaroos have thrived in Australia, where they currently live.
Kangaroos, being marsupials, have a travel advantage over some placental animals. When a marsupial has its young, they can hop into the mother’s pouch, and the mother can continue migrating. In other words, marsupials can travel farther faster than many placentals. This may help explain why marsupials dominated Australia, but more on this in a moment.”

As you probably appreciate the ‘ice age’ stuff is almost entirely utter garbage. Warm oceans are ‘required’! And of course Noah’s Flood provided them!

“The point is that many animals and plants have been redistributed to places all over the world by mankind.” Yet in the 1 minute audio attached to the Guardian newspaper article about the Creation Museum this week Andrew Snelling stated that humans were ‘held up’ around the Tower of Babel before dispersing around the world (and so chimps and the like might have spread across the globe faster than us – and thus not relying on human intervention).

Of course all this is mere speculation – NO scientific evidence of a worldwide inundation 3,400 years’ ago and an ‘ice age’ even more recently.